It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

The hidden lair of an alchemist rediscovered in a 2002 flood.

An Austrian house of bones filled with hundreds of intricately painted skulls.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

100 year tradition of fist fights, marked by marble footsteps.

The fairy tale castle of the "fairy-tale king."

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

An underground city of salt.

American soldiers discovered Europe's best one-liner at the end of World War II.

Op-art architecture designed for happiness.

Macabre museum devoted to historical Viennese murders.

Relive a Polish uprising via an enormous, century-old cyclorama.

Mummified monks and the accidentally interred, in a 17th-century crypt.

Steadily reminding Czechia of its past.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Macabre astrological automaton clock dating to the late 1400s.

Monument to a suicide protesting the Soviet invasion.

Looming communist pillar with a Czech twist.

The sanctuary holds what was once believed to be the saint's incorruptible tongue.

A church of bones, decorated with 40,000 human skeletons.